More particularly, the present invention relates to a pyrotechnical head designed, on contact with or in the proximity of a target, mainly to disperse a pyrotechnical composition comprising one or more pyrotechnical substances selected as a function of the looked-for effect, which may be incendiary and/or incapacitating.
In order to increase the range of incendiary and/or incapacitating weapons, proposals have been made to mount a pyrotechnical head on a projectile, the head comprising an envelope filled with a pyrotechnical composition and with means for dispersing said composition over the target, which means are conventionally constituted by an explosive charge placed within the pyrotechnical composition. The envelope is ruptured under the effect of the pressure evolved during the explosion of the explosive charge. Known pyrotechnical heads of that type suffer from the drawback of giving rise to non-uniform bursting of the envelope so that the pyrotechnical composition is dispersed over directions and ranges that do not always correspond with the desired dispersal. In particular, during use of pyrotechnical compositions that include an incendiary substance, dispersal must not take place over too great a range, since the substance then becomes difficult to ignite, nor must its range be too confined, since there is then loss of effectiveness.
In order to remedy the above drawback, proposals have been made to pre-fragment the envelope in such a manner as to cause it to burst in a determined manner. Nevertheless, making a pre-fragmented envelope encounters the difficulty of achieving a compromise between dispersal range of the pyrotechnical composition and the extent to which the envelope is pre-fragilized. A powerful explosive charge based in a strong envelope generates high pressure before the envelope ruptures and thus disperses the pyrotechnical composition over a large range. In contrast, an envelope that has been pre-fragilized bursts at a lower pressure, thereby reducing the range over which the pyrotechnical composition is dispersed, while simultaneously providing less mechanical strength for withstanding the acceleration to which the projectile is subjected on being launched or on being handled. In addition, the machining done to pre-fragment an envelope must be accurate and is therefore expensive.
Publication U.S. Pat. No. 3,103,888 describes a pyrotechnical head comprising an elongate envelope, a smoke-generating pyrotechnical composition constituted by white phosphorus contained inside the envelope, and dispersal means for dispersing the composition and for splitting the envelope longitudinally. In that known pyrotechnical head, the dispersal means are disposed in such a manner that the white phosphorus is dispersed little and burns in the form of large lumps like smoke generator pots. Thus, that known head is unsuitable for an incendiary or incapacitating composition where dispersal over a greater range is looked for.